Method for producing a coated cutting tool

Abstract

A method for producing a coated cutting tool includes depositing on every flank face and every rake face of the cutting tool an Al 2 O 3 layer by a HIPIMS process during two-fold or three-fold rotation of the substrates, at a substrate temperature ≥350° C. but <600° C., the deposited Al 2 O 3 layer including α-Al 2 O 3 .

1 . A method for producing a coated cutting tool having at least one rake face and at least one flank face, the method comprising:
 providing a cutting tool having a substrate of cemented carbide, cermet, cBN, or ceramic and a coating;   depositing on each at least one flank face and each at least one rake face of the cutting tool an Al 2 O 3  layer by a HIPIMS process, wherein the process a peak pulse cathode power is ≥500 kW, a value of negative peak pulse voltage is ≥1200 V, a specific target peak pulse power density is ≥350 W/cm 2 , a specific average target power density is ≥6 W/cm 2 , a pulse time is 20-150 s, a pulse frequency is ≥100 Hz, a peak pulse current is ≥400 A, and wherein there is either a pulsed bias, or DC bias, voltage applied of from 150 to 300 V, negative bias, wherein a peak bias current is ≥100 A and ≤800 A, a specific bias current density is 5-80 mA/cm 2 , an oxygen partial pressure is ≥1×10 −4  mbar, and a total pressure is from 0.25 to 3 Pa;   charging a PVD reactor chamber, containing at least one Al target and a rotatable substrate holder, with cutting tool blanks, wherein a target size is from 500 to 3000 cm 2 ; and   depositing an Al 2 O 3  layer in the HIPIMS process during two-fold or three-fold rotation of the substrates, at a substrate temperature ≥350° C. but <600° C., wherein the deposited Al 2 O 3  layer comprises α-Al 2 O 3 .   
     
     
         2 . The method according to  claim 1 , wherein the substrate temperature during the deposition in the HIPIMS process is ≥400° C. but <580° C. 
     
     
         3 . The method according to  claim 1 , wherein in the HIPIMS process the pulse time is from 30 to 100 μs. 
     
     
         4 . The method according to  claim 1 , wherein in the HIPIMS process the peak pulse cathode power is ≥1 MW. 
     
     
         5 . The method according to  claim 1 , wherein in the HIPIMS process the specific target peak pulse current density is ≥0.25 A/cm 2 . 
     
     
         6 . The method according to  claim 1 , wherein in the HIPIMS process the specific target peak pulse power density is ≥650 W/cm 2 . 
     
     
         7 . The method according to  claim 1 , wherein in the HIPIMS process the specific bias current density is 10-40 mA/cm 2 . 
     
     
         8 . The method according to  claim 1 , wherein the deposited Al 2 O 3  layer contains a mixture of α-Al 2 O 3  and γ-Al 2 O 3 . 
     
     
         9 . The method according to  claim 1 , wherein the deposited Al 2 O 3  layer in GIXRD (gracing incidence x-ray diffraction) analysis at a 0.5° incidence angle in an 2theta diffractogram, on at least one of the rake face or flank face of a cutting tool, shows:
 a ratio I(α-Al 2 O 3  (113)) to I(γ-Al 2 O 3  (400)) being ≥0.5, and/or 
 a ratio I(α-Al 2 O 3  (024)) to I(γ-Al 2 O 3  (400)) being ≥0.2, and/or 
 a ratio I(α-Al 2 O 3  (116)) to I(γ-Al 2 O 3  (400)) being ≥0.1. 
 
     
     
         10 . The method according to  claim 1 , wherein the deposited Al 2 O 3  layer is an α-Al 2 O 3  layer. 
     
     
         11 . A coated cutting tool having at least one rake face and at least one flank face, comprising an Al 2 O 3  layer deposited according to the method of  claim 1 , wherein the deposited Al 2 O 3  layer comprises α-Al 2 O 3 . 
     
     
         12 . The coated cutting tool according to  claim 11 , wherein α-Al 2 O 3  is present in the deposited Al 2 O 3  layer on each of the at least one rake face and flank face of the cutting tool. 
     
     
         13 . The coated cutting tool according to  claim 1 , wherein the Al 2 O 3  layer has a Vickers hardness of ≥2000 HV. 
     
     
         14 . The coated cutting tool according to  claim 1 , wherein the Al 2 O 3  layer has a reduced Young's modulus of ≥320 GPa. 
     
     
         15 . The coated cutting tool according to  claim 1 , wherein the Al 2 O 3  layer in GIXRD (gracing incidence x-ray diffraction) analysis at 0.5° incidence angle in an 2theta diffractogram, on at least one of the rake face or flank face of a cutting tool, shows:
 a ratio I(α-Al 2 O 3  (113)) to I(γ-Al 2 O 3  (400)) in an XRD 2theta diffractogram being ≥0.5, and/or 
 a ratio I(α-Al 2 O 3  (024)) to I(γ-Al 2 O 3  (400)) in an XRD 2theta diffractogram being ≥0.2, and/or 
 a ratio I(α-Al 2 O 3  (116)) to I(γ-Al 2 O 3  (400)) in an XRD 2theta diffractogram being ≥0.1.